Dynamo-electric machine



A. L BROWN.

DYNAMO ELECTRIC MACHINE.

APPLICATION man ma. 2. 1914.

1,31 1,638. Y Patented July 29, 1919.

THE COLUMBIA PIANBGIIAPK 120., WASHINGTON, u. c.

UNITED STATES PATENT OFFICE.

ARTHUR J. BROWN, OF MILWAUKEE, WISCONSIN, ASSIGNOR- TO ALLIS-CHALMERSMANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OFDELAWARE.

DYNAMO-ELECTRIC MACHINE.

Specification of Letters Patent.

Patented July 29, 1919.

To all whom it may concern:

Be it known that I, ARTHUR J. Buown, a citizen of the United States,residing at Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented a certain new and useful Improvement in Dynamo-Electric Machines, of which the following is a specification.

This invention relates to dynamo-electric machines and more particularlyto such machines when used for driving a load that may become, at times,extremely heavy, as, for instance, when the machine is used for drivingthe rolls of rolling mills and the like.

In the operation of rolling mills by electric motors, it is desirable toprovide, between the motor and the rolls of the mill, a special form ofcoupling which is designed to withstand smaller torque than the shaftand other rotating parts. I11 case of an overload on the rolls, or otherdriven machinery, this coupling breaks, permitting the motor t run, butwithout load. This coupling serves a purpose very similar to that of afuse in an electric circuit. When such a coupling breaks, it usuallydoes so along an irregular surface, and the two portions of thecoupling, having relative rotation, due to the stoppage or slowing downof the rolls, are forced apart, and. as the roll shaft is held againstend-Wise movement, the motor shaft is caused to move endwise. In somecases, this end thrust on the motor is exceedingly heavy, and unlessspecial means are provided for taking n such thrust, serious damage mayresult to t e motor parts. It will be apparent, then, that it isdesirable that the motor be free to move endwise to a limited extent,when the coupling between the motor shaft and the rolldriving shaftbreaks.

It is the object of the present invention to provide an improvedconstruction in which a motor shaft is permitted to have endwisemovement, due to excessive end thrust, such as occurs on the breaking ofa driving con nection between the motor shaft and a driven shaft, and isheld against such endwise movement during normal operation.

Another object of this invention is to pro vide an improved bearing fora motor shaft, capable, at times, of moving relatively to a fixed partof the motor frame or support.

These and other objects are obtained by this invention, the novelfeatures of which will appear from the description and drawings,disclosing one embodiment of such invention, and will be particularlypointed out in the claims.

In the drawings:

Figure 1 IS a partly sectional elevation of a wound-rotor inductionmotor in Which the invention has been applied, coupled to a shaft whichmay be the driving shaft of a, rolling mill.

Fig. 2 is an enlarged vertical section of a portion of the righthandpedestal and the bearing supported thereby, shown in Fig. 1.

Fig. 3 is a view similar to Fig. l, but show ing the couplin between themotor shaft and the driven siaft broken, and the shaft and rotor of themotor forced to the right.

Fig. 4 is an enlarged section of the righthand bearing and associatedparts shown in Fig. 3, the motor shaft and bearing being forced to theright.

As shown in Fig. 1, fixed supporting pedestals 8 and 9 support a woundrotor 10 of an induction motor, the rotor being mounted on a shaft 11.so as to rot-ate within a stator 12. The shaft 11 is mounted in bearings141 supported on pedestals 8 and 9, respectively, and is connected by acoupling 15 to the shaft 16, which may be the driving shaft of the rollsof a rollin mill, or may be connected to any other esired load. Sev eralcollector rings 17, here shown as three in number, are mounted on asleeve 18, and each collector ring is connected by a flexible connection19 to the proper point or points on the Winding of the rotor 10. Thesleeve 18 fits loosely on the shaft 11, any suitable means beingprovided whereby the sleeve and rings may slide longitudinally of theshaft, but must rotate therewith.

A support 31 is here shown as mounted on the cap 44, carrying brushstuds 32 for brushes 33 which cooperate with rings 17. The support 31also carries one or more inwardly projecting arms, carrying rollers 35at their inner ends. The rollers 35 are disposed in a groove formed inthe sleeve 18 and engage the sides of the groove. The support 31 may bein the form of a ring held in place and extending into the groove 35, orany other construction suitable for the purpose may be used; and,further, any arrangement that is effective to maintain the brushes incontact with the collector rings connected to the rotor winding, inspite of any movement of the rotor shaft due to exoessive end-thrust,may be used instead of the construction shown.

For a detail view of the bearing 141 and its associated parts referencemay be had to Fig. 2. The pedestal 9 has its upper portion recessed at41 and is provided with an interior portion 42 adapted to form a seat. Acap or shell 44, recessed similar to the upper portion of the pedestal,is provided with a portion or seating surface 42 adapted to aline withthe portion 42 of the pedestal, when the cap is secured in operativeposition relatively to the pedestal, as by bolts 46. The seat portions42 and 42' may be disposed centrally of the pedestal and cap,respectively, and the two alined parts may present a smooth polygonal orcylindrical surface, to form a seat for a bearing 141, which may be ofany type suitable to provide perfect alinement of the shaft 11 carriedthereby. If the engaging surfaces of the parts 42 and 42" and bearing141 are cylindrical, a feather 47 may be used to prevent rotation of thebearing in the pedestal and cap. The bearing is normally held againstendwise movement relative to the pedestal and cap by means of bolts 21engaging the cap or pedestal and the bearing, being here shown aspassing through a portion of the bearing, heads or nuts on the boltsbeing effective to hold one or more recessed portions 48 on the bearingagainst one or more shoulders 49 on the cap or pedestal. A reducedportion of the shaft 11 passes through the bearing 141 and is limited tocomparatively little endwise movement relatively thereto by the collars50 and 51 on the shaft engaging portions of the bearing. A bumper collar52 on the shaft 11, by engagement with a portion of the pedestal or cap,serves to limit the endwise movement of the shaft, when the same hasbeen subjected to such excessive endwise thrust .as is capable ofshifting the hearing.

In the construction illustrated. the motor and bearing parts arenormally in the positions shown in Figs. 1 and 2. However, when the loadon the shaft 16 becomes excessive and the coupling 15 breaks, this breakbeing always along a rough or uneven surface which is generally somewhatdiagonal, the shaft 11 is moved endwise, the thrust on the shaft beingsufficient to cause the breaking of the bolts 21 and the endwisemovement of the bearing 141 relative to the pedestal and cap, thismovement occurring through the engagement of the collar 50 with thebearing. The bearing is free to move a sufiicient distance to allow thebroken parts of the coupling 16 to clear each other, and its movement islimited by ongagement of the bumper collar 52 on the shaft with aportion of the cap or pedestal. Figs. 3 and 4 show the parts in therelative positions that they occupy when the coupling 16 is broken andthe motor shaft has con moved endwise.

In assembling the bearing in operative position, the breakable bolts 2'1in the cap portion of the support, may be manipulated through openings52.

As the connection between the shaft and bearing is such as preventsappreciable relative longitudinal movement, it will be obvious that theshaft, itself, or any art connected thereto, may form the movaleabutment for breakable bolts.

Although the invention is here shown as applied to a wound-rotorinduction motor, it is also applicable to other forms of motors and, infact, to a generator or any other machine, which -may be coupled to adriving source, and which it is desirable to protect from the injuriouseffects of excessive endwise thrust that may result on the breaking ofthe shaft connection between the machine and the driving means, or fromany other source.

It should be understood that it is not desired to be limited to theexact details of construction shown and described, for Ohviousmodifications will occur to a person skilled in the art.

It is claimed and desired to secure by Letters Patent:

In combination with a machine comprising a rotatable part mounted on ashaft, a bearing housing, a bearing for said shaft within said housing,said shaft and said bearing being held against appreciable relativelongitudinal movement, and means comprising a plurality of boltsdisposed within said housing and having frangible portions forpreventing movement of said bearing relative to said housing andpermitting only axial movement of said shaft and said bearing on theoccurrence of excessive end thrust on said shaft.

In testimony whereof the si ature of the inventor is aflixed hereto in te presence of two witnesses.

ARTHUR J. BROWN. Witnesses:

W. H. LIEBER, J. J. KANE.

(topics of this patent may be obtained for live units each, byaddressing the Commissioner of Patents.

Washington, D. 0."

